People saying that DPS are more important than Healers do have a point. Although it's just an opinion (which I mostly agree with).
I've healed BGs as a disc priest for about 60k HKs (yeah, i'm using HKs as a reference of time). I got so sick and tired of healing DPS that did not know how to play properly. They did not interrupt, did not chain CC, did not focus targets. I switched my main spec to shadow and have been making a huge impact in many more games ever since.
As a (I would say) competent DPS, I am able to out perform most people on both teams. I'm able to 1v2 people, and get a flag return. I'm able to shut down healers for a period of time and burst down DPS. I'm able to pull top numbers every fight (KBs, DMG, Objectives). As a healer, I felt as if I'm prolonging the game with people who could not do these things.